The present invention relates to apparatus for transferring containers, such as cylindrical drums or pails from a receiving station to a loading station and for arranging the pails at the loading station in a predetermined array. Such apparatus are generally known as "palletizers" because the pails are subsequently placed on pallets, and the present invention is directed to a novel method and apparatus for arranging the pails in preselected space-saving arrays.
Exemplary palletizing apparatus are disclosed in U.S. Pat. No. 3,902,594 entitled "Apparatus for Arranging and Stacking Containers" and a co-pending application of applicants' assignee entitled "Variable Array Can Palletizer", Ser. No. 017,179, filed on Mar. 5, 1979; now U.S. Pat. No. 4,316,693. Each of these palletizers includes a carriage which is rectilinearily shiftable on a frame structure between a receiving station and a stacking or loading station. The carriage includes gripping devices which comprise a plurality of clamping arms operable for clamping onto the rim of a drum or pail so that a plurality of pails may be lifted from the receiving station, shifted toward the loading station and deposited thereon. The carriage is then returned, and a new row of pails may be positioned adjacent the first row of the pails.
With respect to the U.S. Pat. No. 3,902,594, the apparatus disclosed therein only provides that adjacent rows are aligned with the center lines of the pails lying along generally parallel lines. With respect to the co-pending application, it is possible to utilize the apparatus disclosed therein for nesting pails so that adjacent rows define either equilateral triangles between the central axes of adjacent pails in the rows or nesting whereby isosceles triangles may be provided.
However, a significant problem exists in loading pails of predetermined diameters onto pallets if the pallets are required to be subsequently loaded into a space having predetermined minimal dimensions. For instance, paint and other materials are often contained within cylindrical containers or pails having lids which have diameters of twelve inches. Most standard tractor-trailer rigs have trailers with outside-to-outside width dimensions of eight feet or 96 inches. However, the thickness of the trailer walls make the inside width of a trailer something less than 96 inches, say 90 inches. Thus, it can be appreciated that if it is desired to load pails having twelve inch diameter lids into such a trailer, a total of eight twelve inch pails may not be positioned with their center lines lying on a common line across the inside width of the trailer. It becomes necessary to nest the pails in rows so that between at least a pair of the rows, the center axes of adjacent pails in the rows define equilateral triangles. In this manner, it may be possible to load pallets, as in rows of four with at least a pair of the rows being nested on each pallet so that a pair of side-by-side positioned pallets may be loaded into the trailer and include a total of eight rows with the above-described nesting of the pails. At least two of the rows, on each pallet, will have their center lines of adjacent pails substantially parallel.
Thus, it becomes necessary to provide an apparatus which will permit stacking or loading of pails on a pallet or other support in which a pair of rows may be nested, as described above, and separate rows may be provided with the center lines of the pails substantially parallel. Prior art palletizing apparatus, such as described in the U.S. Pat. No. 3,902,594 and the co-pending application do not enable nesting of rows followed by rows in which the center lines of the pails lie on parallel lines. This is because each of the above prior art apparatus utilize clamping jaws or arms for engaging and gripping a pail. A total of three clamping arms are used for gripping the lid of a pail with the arms being angularly disposed about a central axis relative to one another at, for instance, 90.degree., 135.degree. and 135.degree.. It is necessary to provide at least three clamping arms per pail in order to adequately grip and lift a pail. However, it can be readily appreciated that if a row, of say four pails are picked up by associated clamping arms and shifted to an aligned first row, it will be impossible to place a second aligned row adjacent the first aligned row because the clamping jaws will be interposed between the first and second row. It is necessary to provide some type of rotation to the clamping jaws so that the jaws do not interfere with placement of the second row against the first row.
Accordingly, it is a general object of the present invention to provide a method and apparatus for transferring an article or articles, such as pails, from a first station to a second station so that the articles may be loaded at the second station in a preselected space-saving array which includes a carriage operable for selective shifting along a path between the first and second stations and a gripping device mounted on the carriage operable for selectively gripping and releasing the articles in which an orienting means is connected to the gripping means operable for selectively imparting rotation thereto.
Another object of the present invention is to provide an apparatus, as described above, in which the carriage means also includes first and second subcarriages. The first subcarriage is mounted on the carriage means and is operable for selective and reciprocal shifting in a substantially vertical direction relative to the carriage means. The second subcarriage is mounted on the first subcarriage for carrying the gripping means and also includes shifting means for selectively shifting the second subcarriage relative to the first subcarriage. Thus, assuming that a row of pails are disposed at the first station, the first carriage means is shifted to a position thereabove and the second subcarriage is suitably disposed with each of the clamping means above an associated pail. The first subcarriage is then downwardly shifted until the clamping means engage the pails for clamping action and then is shifted vertically upwardly to remove the pails from the loading station. The carriage means is then horizontally shifted until it is disposed above the first station.
The pails are then deposited in a first row and the carriage means is shifted to pick up a second row. A second row is picked up and during shifting toward the second station by the carriage means, the second subcarriage is shifted along the first subcarriage so that the pails of the second row may be nested against the pails of the first row so that the center line of the pails in adjacent rows are disposed at an angle relative to each other. Then, when the carriage means is returned to the first station, the orienting means is operated to rotate so that when pails of a third row are picked up at the first station, they may be subsequently transported to the second station so that they are aligned against the second row so that the second and third rows have the pail center lines parallel to one another.
These and additional objects and advantages of the present invention will be more clearly understood after a consideration of the drawings and the detailed description of the preferred embodiment.